Mineral springs contain a high proportion of mineral salts in solution, including calcium carbonate, magnesium sulfate, potassium, and sodium sulfate. Formed through natural geological processes and through the decomposition and fossilization of animals, the mineral matter gives water a deﬁnite taste, distinct from ordinary drinking water. A mineral spring is often described in terms of its principal characteristic constituent—for example, salt spring or sulfur spring. Given their therapeutic value for the treatment of rheumatism, arthritis, skin diseases, and various other ailments, sulfur springs have become popular sites for spas and resorts worldwide, such as those at Saratoga Springs in upstate New York. The United States and Canada have over two hundred commercial hot springs and mineral springs, along with thousands of smaller noncommercial springs.